TYPES OF BACTERIA FOUND IN MILK 2Q 



It is possible that this type should really be divided into two, 

 one of which is a Streptococcus and the other a Bacterium. 

 This seems to be the conclusion of recent works. 1 But these 

 two are in other respects almost alike and in our review here 

 it is not wise to try to make this distinction. 2 



Isolation of Bacterium Lactic Acidi. It is an extremely 

 easy matter to obtain this organism from milk, as foHows: 



A sample of milk that has become somewhat sour, but has not 

 yet curdled, should be used for the purpose. This will contain 

 millions of bacteria, and should be very highly diluted for the 

 experiment. A dilution of one to a million is not too high for 

 the purpose. Litmus gelatin plates should be made as de- 

 scribed in experiment n. These are to be kept at about 70 for 

 two to four days when they will be found filled with minute red 

 points, or colonies. These are colonies of lactic acid bacteria. 

 On such a plate will likely be found, however, several kinds of 

 colonies, and perhaps two or three types of acid colonies. But 

 the colonies of the Bad. lactis acidi can, when the plates 

 are properly made, be distinguished from others by the use 

 of a low magnifying power under the microscope. Each of the 

 colonies is found to be quite red, very small, and growing 

 wholly underneath the surface of the gelatin. Examination 

 with a microscope shows an appearance like figure 16, the most 



1 Lohnis. Cent. f. Bact., II., xviii., p. 97, 1907. 



2 Besides the names given above the following names have been applied to 

 lactic acid bacteria that are in essential respects like the one described and 

 should at least be regarded as belonging to the same group: 



Bact. or Streptococcus Guntheri. 

 Streptococcus acidi lactici. 

 Bact. acidi paralactica. 

 Bact. lactis acidi aromaticum. 

 Bact. lactis acidi maltigeum. 

 Bact. lactis acidi pvrvm. 

 Bact. lactis acidi acerbum. 

 Staphylococcus lactis acidi. 



These are all by some regarded as identical with the common pathogenic 

 form Strep, pyogenes. Heinemann. Jour. Infec. Dis., IV., p. 87, 1907. 



